asm	mov	ds,ax

}


/*
======================
=
= CAL_CarmackExpand
=
= Length is the length of the EXPANDED data
=
======================
*/

#define NEARTAG	0xa7
#define FARTAG	0xa8

void CAL_CarmackExpand (unsigned far *source, unsigned far *dest, unsigned length)
{
	unsigned	ch,chhigh,count,offset;
	unsigned	far *copyptr, far *inptr, far *outptr;

	length/=2;

	inptr = source;
	outptr = dest;

	while (length)
	{
		ch = *inptr++;
		chhigh = ch>>8;
		if (chhigh == NEARTAG)
		{
			count = ch&0xff;
			if (!count)
			{				// have to insert a word containing the tag byte
				ch |= *((unsigned char far *)inptr)++;
				*outptr++ = ch;
				length--;
			}
			else
			{
				offset = *((unsigned char far *)inptr)++;
				copyptr = outptr - offset;
				length -= count;
				while (count--)
					*outptr++ = *copyptr++;
			}
		}
		else if (chhigh == FARTAG)
		{
			count = ch&0xff;
			if (!count)
			{				// have to insert a word containing the tag byte
				ch |= *((unsigned char far *)inptr)++;
				*outptr++ = ch;
				length --;
			}
			else
			{
				offset = *inptr++;
				copyptr = dest + offset;
				length -= count;
				while (count--)
					*outptr++ = *copyptr++;
			}
		}
		else
		{
			*outptr++ = ch;
			length --;
		}
	}
}



/*
======================
=
= CA_RLEWcompress
=
======================
*/

long CA_RLEWCompress (unsigned huge *source, long length, unsigned huge *dest,
  unsigned rlewtag)
{
  long complength;
  unsigned value,count,i;
  unsigned huge *start,huge *end;

  start = dest;

  end = source + (length+1)/2;

//
// compress it
//
  do
  {
	count = 1;
	value = *source++;
	while (*source == value && source<end)
	{
	  count++;
	  source++;
	}
	if (count>3 || value == rlewtag)
	{
    //
    // send a tag / count / value string
    //
      *dest++ = rlewtag;
      *dest++ = count;
      *dest++ = value;
    }
    else
    {
    //
    // send word without compressing
    //
      for (i=1;i<=count;i++)
	*dest++ = value;
	}

  } while (source<end);

  complength = 2*(dest-start);
  return complength;
}


/*
======================
=
= CA_RLEWexpand
= length is EXPANDED length
=
======================
*/

void CA_RLEWexpand (unsigned huge *source, unsigned huge *dest,long length,
  unsigned rlewtag)
{
//  unsigned value,count,i;
  unsigned huge *end;
  unsigned sourceseg,sourceoff,destseg,destoff,endseg,endoff;


//
// expand it
//
#if 0
  do
  {
	value = *source++;
	if (value != rlewtag)
	//
	// uncompressed
	//
	  *dest++=value;
	else
	{
	//
	// compressed string
	//
	  count = *source++;
	  value = *source++;
	  for (i=1;i<=count;i++)
	*dest++ = value;
	}
  } while (dest<end);
#endif

  end = dest + (length)/2;
  sourceseg = FP_SEG(source);
  sourceoff = FP_OFF(source);
  destseg = FP_SEG(dest);
  destoff = FP_OFF(dest);
  endseg = FP_SEG(end);
  endoff = FP_OFF(end);


//
// ax = source value
// bx = tag value
// cx = repeat counts
// dx = scratch
//
// NOTE: A repeat count that produces 0xfff0 bytes can blow this!
//

asm	mov	bx,rlewtag
asm	mov	si,sourceoff
asm	mov	di,destoff
asm	mov	es,destseg
asm	mov	ds,sourceseg

expand:
asm	lodsw
asm	cmp	ax,bx
asm	je	repeat
asm	stosw
asm	jmp	next

repeat:
asm	lodsw
asm	mov	cx,ax		// repeat count
asm	lodsw			// repeat value
asm	rep stosw

next:

asm	cmp	si,0x10		// normalize ds:si
asm  	jb	sinorm
asm	mov	ax,si
asm	shr	ax,1
asm	shr	ax,1
asm	shr	ax,1
asm	shr	ax,1
asm	mov	dx,ds
asm	add	dx,ax
asm	mov	ds,dx
asm	and	si,0xf
sinorm:
asm	cmp	di,0x10		// normalize es:di
asm  	jb	dinorm
asm	mov	ax,di
asm	shr	ax,1
asm	shr	ax,1
asm	shr	ax,1
asm	shr	ax,1
asm	mov	dx,es
asm	add	dx,ax
asm	mov	es,dx
asm	and	di,0xf
dinorm:

asm	cmp     di,ss:endoff
asm	jne	expand
asm	mov	ax,es
asm	cmp	ax,ss:endseg
asm	jb	expand

asm	mov	ax,ss
asm	mov	ds,ax

}



/*
=============================================================================

					 CACHE MANAGER ROUTINES

=============================================================================
*/


/*
======================
=
= CAL_SetupGrFile
=
======================
*/

void CAL_SetupGrFile (void)
{
	char fname[13];
	int handle;
	memptr compseg;

#ifdef GRHEADERLINKED

	grhuffman = (huffnode *)&EGAdict;
	grstarts = (long _seg *)FP_SEG(&EGAhead);

	CAL_OptimizeNodes (grhuffman);

#else

//
// load ???dict.ext (huffman dictionary for graphics files)
//

	strcpy(fname,gdictname);
	strcat(fname,extension);

	if ((handle = open(fname,
		 O_RDONLY | O_BINARY, S_IREAD)) == -1)
		CA_CannotOpen(fname);

	read(handle, &grhuffman, sizeof(grhuffman));
	close(handle);
	CAL_OptimizeNodes (grhuffman);
//
// load the data offsets from ???head.ext
//
	MM_GetPtr (&(memptr)grstarts,(NUMCHUNKS+1)*FILEPOSSIZE);

	strcpy(fname,gheadname);
	strcat(fname,extension);

	if ((handle = open(fname,
		 O_RDONLY | O_BINARY, S_IREAD)) == -1)
		CA_CannotOpen(fname);

	CA_FarRead(handle, (memptr)grstarts, (NUMCHUNKS+1)*FILEPOSSIZE);

	close(handle);


#endif

//
// Open the graphics file, leaving it open until the game is finished
//
	strcpy(fname,gfilename);
	strcat(fname,extension);

	grhandle = open(fname, O_RDONLY | O_BINARY);
	if (grhandle == -1)
		CA_CannotOpen(fname);


//
// load the pic and sprite headers into the arrays in the data segment
//
	MM_GetPtr(&(memptr)pictable,NUMPICS*sizeof(pictabletype));
	CAL_GetGrChunkLength(STRUCTPIC);		// position file pointer
	MM_GetPtr(&compseg,chunkcomplen);
	CA_FarRead (grhandle,compseg,chunkcomplen);
	CAL_HuffExpand (compseg, (byte huge *)pictable,NUMPICS*sizeof(pictabletype),grhuffman,false);
	MM_FreePtr(&compseg);
}

//==========================================================================


/*
======================
=
= CAL_SetupMapFile
=
======================
*/

void CAL_SetupMapFile (void)
{
	int	i;
	int handle;
	long length,pos;
	char fname[13];

//
// load maphead.ext (offsets and tileinfo for map file)
//
#ifndef MAPHEADERLINKED
	strcpy(fname,mheadname);
	strcat(fname,extension);

	if ((handle = open(fname,
		 O_RDONLY | O_BINARY, S_IREAD)) == -1)
		CA_CannotOpen(fname);

	length = filelength(handle);
	MM_GetPtr (&(memptr)tinf,length);
	CA_FarRead(handle, tinf, length);
	close(handle);
#else

	tinf = (byte _seg *)FP_SEG(&maphead);

#endif

//
// open the data file
//
#ifdef CARMACIZED
	strcpy(fname,"GAMEMAPS.");
	strcat(fname,extension);

	if ((maphandle = open(fname,
		 O_RDONLY | O_BINARY, S_IREAD)) == -1)
		CA_CannotOpen(fname);
#else
	strcpy(fname,mfilename);
	strcat(fname,extension);

	if ((maphandle = open(fname,
		 O_RDONLY | O_BINARY, S_IREAD)) == -1)
		CA_CannotOpen(fname);
#endif

//
// load all map header
//
	for (i=0;i<NUMMAPS;i++)
	{
		pos = ((mapfiletype	_seg *)tinf)->headeroffsets[i];
		if (pos<0)						// $FFFFFFFF start is a sparse map
			continue;

		MM_GetPtr(&(memptr)mapheaderseg[i],sizeof(maptype));
		MM_SetLock(&(memptr)mapheaderseg[i],true);
		lseek(maphandle,pos,SEEK_SET);
		CA_FarRead (maphandle,(memptr)mapheaderseg[i],sizeof(maptype));
	}

//
// allocate space for 3 64*64 planes
//
	for (i=0;i<MAPPLANES;i++)
	{
		MM_GetPtr (&(memptr)mapsegs[i],64*64*2);
		MM_SetLock (&(memptr)mapsegs[i],true);
	}
}


//==========================================================================


/*
======================
=
= CAL_SetupAudioFile
=
======================
*/

void CAL_SetupAudioFile (void)
{
	int handle;
	long length;
	char fname[13];

//
// load maphead.ext (offsets and tileinfo for map file)
//
#ifndef AUDIOHEADERLINKED
	strcpy(fname,aheadname);
	strcat(fname,extension);

	if ((handle = open(fname,
		 O_RDONLY | O_BINARY, S_IREAD)) == -1)
		CA_CannotOpen(fname);

	length = filelength(handle);
	MM_GetPtr (&(memptr)audiostarts,length);
	CA_FarRead(handle, (byte far *)audiostarts, length);
	close(handle);
#else
	audiohuffman = (huffnode *)&audiodict;
	CAL_OptimizeNodes (audiohuffman);
	audiostarts = (long _seg *)FP_SEG(&audiohead);
#endif

//
// open the data file
//
#ifndef AUDIOHEADERLINKED
	strcpy(fname,afilename);
	strcat(fname,extension);

	if ((audiohandle = open(fname,
		 O_RDONLY | O_BINARY, S_IREAD)) == -1)
		CA_CannotOpen(fname);
#else
	if ((audiohandle = open("AUDIO."EXTENSION,
		 O_RDONLY | O_BINARY, S_IREAD)) == -1)
		Quit ("Can't open AUDIO."EXTENSION"!");
#endif
}

//==========================================================================


/*
======================
=
= CA_Startup
=
= Open all files and load in headers
=
======================
*/

void CA_Startup (void)
{
#ifdef PROFILE
	unlink ("PROFILE.TXT");
	profilehandle = open("PROFILE.TXT", O_CREAT | O_WRONLY | O_TEXT);
#endif

	CAL_SetupMapFile ();
	CAL_SetupGrFile ();
	CAL_SetupAudioFile ();

	mapon = -1;
	ca_levelbit = 1;
	ca_levelnum = 0;

}

//==========================================================================


/*
======================
=
= CA_Shutdown
=
= Closes all files
=
======================
*/

void CA_Shutdown (void)
{
#ifdef PROFILE
	close (profilehandle);
#endif

	close (maphandle);
	close (grhandle);
	close (audiohandle);
}

//===========================================================================

/*
======================
=
= CA_CacheAudioChunk
=
======================
*/

void CA_CacheAudioChunk (int chunk)
{
	long	pos,compressed;
#ifdef AUDIOHEADERLINKED
	long	expanded;
	memptr	bigbufferseg;
	byte	far *source;
#endif

	if (audiosegs[chunk])
	{
		MM_SetPurge (&(memptr)audiosegs[chunk],0);
		return;							// allready in memory
	}

//
// load the chunk into a buffer, either the miscbuffer if it fits, or allocate
// a larger buffer
//
	pos = audiostarts[chunk];
	compressed = audiostarts[chunk+1]-pos;

	lseek(audiohandle,pos,SEEK_SET);

#ifndef AUDIOHEADERLINKED

	MM_GetPtr (&(memptr)audiosegs[chunk],compressed);
	if (mmerror)
		return;

	CA_FarRead(audiohandle,audiosegs[chunk],compressed);

#else

	if (compressed<=BUFFERSIZE)
	{
		CA_FarRead(audiohandle,bufferseg,compressed);
		source = bufferseg;
	}
	else
	{
		MM_GetPtr(&bigbufferseg,compressed);
		if (mmerror)
			return;
		MM_SetLock (&bigbufferseg,true);
		CA_FarRead(audiohandle,bigbufferseg,compressed);
		source = bigbufferseg;